1. Field of the Invention
This invention relates to a method and an apparatus for retrieving a desired content from music contents in a recording medium, and then playing back the retrieved content.
2. Description of the Related Art
Japanese patent application publication number 09-034909/1997 discloses an information retrieval apparatus including a database which stores files of multimedia data containing sound information. Each file has an added factor vector representing file's position in a factor coordinate space. A user inputs information about a desired file (desired data). The inputted information represents desired-file's position in an adjective coordinate space defined by pairs of adjectives and their antonyms expressing human sensitivities. The inputted information is converted, being mapped onto the factor coordinate space so that the desired-file's position will be in the factor coordinate space. The distances between the database-file's positions and the desired-file's position in the factor coordinate space are computed. Among the database files, ones are selected which correspond to the computed distances smaller than a prescribed value. The selected database files are searched for a target matching the desired file.
In the apparatus of Japanese application 09-034909/1997, the user is required to input parameter values for the respective pairs of adjectives and their antonyms as information about a desired file. Therefore, the user is forced to take a long time in this regard. It tends to be difficult for the user to input parameter values without referring to references.
Japanese patent application publication number 2005-010854 corresponding to U.S. patent application publication number US 2005/0010599 A1 discloses an information presenting system in which files of music pieces are represented in symbols such as stars, and are clustered based on their attributes so as to be allocated in an information space defined by the attributes. Regarding one of the attributes, an impression, such as “refreshing”, on the music piece corresponding to a file is represented and given in the form of emotion. The initial search for a desired file is carried out by roughly cutting out a marked-out space from the information space in response to user's operation. When the area containing candidate files is narrowed down, the candidate files are linearly developed so as to support user's selection.
In the system of Japanese application publication number 2005-010854, a display can indicate the information space as a three-dimensional picture. To properly indicate a three-dimensional picture, the display is required to be large in size. Among input devices of various types, only strictly limited ones can be used as an operation unit for accepting user's operation.
Japanese patent application publication number 2002-278547 discloses a system composed of a music-piece registering section, a music-piece database, and a music-piece retrieving section. The music-piece registering section registers audio signals representing respective music pieces and ancillary information pieces relating to the respective music pieces in the music-piece database. Each audio signal representing a music piece and an ancillary information piece relating thereto are in a combination within the music-piece database. Each ancillary information piece has an ID, a bibliographic information piece, acoustic feature values (acoustic feature quantities), and impression values about a corresponding music piece. The bibliographic information piece represents the title of the music piece and the name of a singer or a singer group vocalizing in the music piece.
The music-piece registering section in the system of Japanese application 2002-278547 analyzes each audio signal to detect the values (the quantities) of acoustic features of the audio signal. The detected acoustic feature values are registered in the music-piece database. The music-piece registering section converts the detected acoustic feature values into values of a subjective impression about a music piece represented by the audio signal. The impression values are registered in the music-piece database.
The music-piece retrieving section in the system of Japanese application 2002-278547 responds to user's request for retrieving a desired music piece. The music-piece retrieving section computes impression values of the desired music piece from subjective-impression-related portions of the user's request. Bibliographic-information-related portions are extracted from the user's request. The computed impression values and the extracted bibliographic-information-related portions of the user's request are combined to form a retrieval key. The music-piece retrieving section searches the music-piece database in response to the retrieval key for ancillary information pieces similar to the retrieval key. Music pieces corresponding to the found ancillary information pieces (the search-result ancillary information pieces) are candidate ones. The music-piece retrieving section selects one from the candidate music pieces according to user's selection or a predetermined selection rule. The search for ancillary information pieces similar to the retrieval key has the following steps. Matching is implemented between the extracted bibliographic-information-related portions of the user's request and the bibliographic information pieces in the music-piece database. Similarity between the computed impression values and the impression values in the music-piece database are calculated. From the ancillary information pieces in the music-piece database, ones are selected on the basis of the matching result and the calculated similarities.
Japanese patent application publication number 6-290574/1994 discloses a music-piece retrieval apparatus in which a primary index of each music piece is a bibliographic item about the music piece such as a title thereof. Acoustic features such as a rhythm-related feature and a chord-related feature are derived from audio data representing each music piece. The derived acoustic features are labeled a secondary index of the music piece. A tertiary index of each music piece is generated on the basis of the secondary index thereof. The tertiary index represents subjective and emotional features of the music piece. There are storages which store primary, secondary, and tertiary indexes of many music pieces. To implement retrieval, a user inputs conditions of a desired music piece which are designed to correspond to primary, secondary, and tertiary indexes of the desired music piece. The inputted conditions are compared with the stored primary, secondary, and tertiary indexes of the music pieces. The comparison is to find, among the stored primary, secondary, and tertiary indexes of the music pieces, a set of primary, secondary, and tertiary indexes of at least one music piece which matches the inputted conditions. The music piece corresponding to the found set of primary, secondary, and tertiary indexes is selected as a retrieval result regarding the desired music piece.
In the music-piece retrieval apparatus of Japanese application 6-290574/1994, the derivatives of the acoustic powers of audio data representing each music piece are computed for each prescribed time interval (each frame). The autocorrelation of the power derivatives is calculated. The calculated autocorrelation varies as a function of a frequency parameter or a period parameter. A value of the frequency parameter or the period parameter is decided at which the calculated autocorrelation is maximized. One of the derived acoustic features is generated on the basis of the decided value of the frequency parameter or the period parameter.